1. Field of the Invention
The present invention relates to optical disc playback apparatuses and, more specifically, to an optical disc playback apparatus for displaying, on a television screen, an on-screen message in the predetermined number of lines changeable to an image display format of data recorded on an optical disc being played back.
2. Description of the Background Art
Recently, video CD players which are CD players incorporated with MPEG1 (Moving Picture Coding Experts Group1) decoding feature are widely available. Such video CD players are capable of reproducing images and sounds for maximum of 74 minutes from moving picture data and audio data recorded on video CDs and Karaoke CDs, wherein such data is digitally compressed by MPEG1 technique. Further,CVDs (China Video CDs) and SVCDs (Super Video CDs) with higher quality of image and audio data are commercialized especially focusing on the Chinese market. The CVDs and the SVCDs are realized with MPEG2 (Moving Picture Coding Experts Group2) decoding featureinstead of MPEGI, and can be played back without any modification on mechanism such as optical pickup, servo technique, and signal processing technique for the MPEG1.
Mainly in the Japanese and US markets, DVD players incorporated with the MPEG2 decoding feature are commercialized. The DVD players are capable of reproducing maximum of 133 minutes of high-quality moving pictures with high-resolution defined by horizontally 702 dots and vertically 480 lines, together with high-quality sound. In addition to the higher quality of reproduced images and sounds, advanced features are achieved in these video CD players and DVD players. Such advanced features are quite convenient for sophisticated users who are familiar with such features to enjoy various functions. On the other hand, it is difficult for ordinary users due to complicated operation required to utilize the functions. To ease the user""s inconvenience caused by the complicated operability, the video CD players and DVD players recently adopt an OSD (On-Screen Display) function. The function is for displaying information for user""s easy operation on a monitor for reproduced pictures. Such information indicates input information corresponding to user""s operation, an elapsed time after start of reproduction, a status of the player during reproduction, special reproduction function, and a type of optical disc. The information is referred to as an on-screen message (OSM).
Hereinafter, by referring to FIGS. 10, 11, and 12, examples of conventional optical disc playback apparatuses are described. In FIG. 10, a first example of the conventional optical disc playback apparatus is shown. In a conventional optical disc playback apparatus OPC1 of this example, an optical disc Od, typically a music CD, is fixedly placed on a spindle motor 72 for rotation. An optical pickup 73 applies a laser beam Lb onto the recording surface of the rotating optical disc Od to read out data therefrom as digital signals.
An optical servo controller 74 executes a servo-control of the spindle motor 72 and the optical pickup 73. A digital signal processor 75 demodulates the digital signals from the optical pickup 73 to convert the signals into sub-code information, control information, a sequence of CD-DA signals unique to the music CD, and a sequence of other signals. Based on the sub-code information and the control information supplied from the digital signal processor 75, a system controller 76 determines the type of the optical disc being played back and detects system errors such as track jumps and focus errors of the laser beam Lb.
An information signal sequence separator 79 separates the digital signal sequences supplied from the digital signal processor 75 into the CD-DA signal sequence and the other signal sequence.
An MPEG1 decoder 78 receives the CD-DA signal sequence and the other signal sequence from the information signal sequence separator 79. If the CD-DA signal sequence is received, the MPEG1 decoder 78 outputs the received signal sequence as it is by using memory 77 as buffer memory. On the other hand, if the signal sequence other than the CD-DA signal sequence is received, the MPEG1 decoder 78 reads disc information on the optical disc Od to determine whether the image display format of the video recorded thereon (signal sequence other than the CD-DA signal sequence) is the PAL or the NTSC.
Further, by using the memory 77 as buffer memory, the MPEG1 decoder 78 converts the video signal sequence (signal sequence other than the CD-DA signal sequence) in real time into a decoded digital signal sequence. Note that if the video is in the PAL format, the video signal sequence is converted into a decoded digital signal sequence in the PAL format. If the video is in the NTSC format, the video signal sequence is converted into a decoded digital signal sequence in the NTSC format.
An on-screen display controller 7A converts character data and character display information from the system controller 76 into a digital character signal sequence.
A video signal D/A converter 7B converts the decoded digital signal sequence from the MPEG1 decoder 78 and the digital character signal sequence from the on-screen display controller 7A into analog video signals.
An audio signal D/A converter 7C converts the CD-DA signal sequence from the MPEG1 decoder 78 into analog audio signals.
The playback operations of the optical disc playback apparatus OPC1 are described with respect to a music CD and other type of optical disc, respectively. For playing back the music CD, the digital signal processor 75 starts demodulation of the digital signals and then outputs the control information and the sub-code information.
When the system controller 76 determines that the signal sequence is the CD-DA signal sequence based on the control information and the sub-code information, the system controller 76 judges that no video signal sequence is recorded on the optical disc Od. In such case, the system controller 76 transmits a control instruction instructing the digital signal processor 75 to output border color signals (normally blue-back) in the NTSC format instead of the video signals. The system controller 76 further outputs the character display information and the character data to the on-screen display controller 7A.
The system controller 76 monitors the system errors such as track lumps and focus errors. Whenever such error occurs, the system controller 76 instructs the optical servo controller 74 so that the optical pickup 73 and the spindle motor 72 return to initial states thereof.
The MPEG1 decoder 78 receives the CD-DA signal sequence from the digital signal processor 75 and outputs the same by using the memory 77 as buffer memory. The MPEG1 decoder 78 also converts the border color signals in the NTSC format from the digital signal processor 75 into the decoded digital signal sequence.
The on-screen display controller 7A receives the character display information from the system controller 76, and sets the number of character display lines of an on-screen message to 10. The on-screen display controller 7A further receives and converts the character data into the digital character signal sequence.
The video signal D/A converter 7B converts the decoded digital signal sequence from the MPEG1 decoder 78 and the digital character signal sequence from the on-screen display controller 7A into the analog video signals.
The audio signal D/A converter 7C converts the CD-DA signal sequence from the MPEG1 decoder 78 into the analog audio signals.
Described next is the operation of the optical disc playback apparatus OPC1 for playing back the optical disc Od other than the music CD. For playing back the optical disc Od, the digital signal processor 75 starts demodulation of the digital signals and then outputs the control information and the sub-code information as well as the signal sequence other than the CD-DA signal sequence.
Based on the control information and the sub-code information from the digital signal processor 75, the system controller 76 judges that the signal sequence is other than the CD-DA signal sequence. The system controller 76 also monitors the system errors such as track jumps and focus errors. Whenever such error occurs, the system controller 76 instructs the optical servo controller 74 so that the optical pickup 73 and the spindle motor 72 return to initial states thereof.
The information signal sequence separator 79 separates the digital signal sequences from the digital signal processor 75 into the CD-DA signal sequence and the other signal sequence.
The MPEG1 decoder 78 receives the CD-DA signal sequence and the other signal sequence from the information signal sequence separator 79. The MPEG1 decoder 78 converts, in real time, the video signal sequence into a decoded digital signal sequence in the PAL format if the video recorded on the optical disc Od is in the PAL format, and into a decoded digital signal sequence in the NTSC format, if in the NTSC format.
The on-screen display controller 7A receives the character display information from the system controller 76, and sets the number of character display lines of an on-screen message to 10. Further, the on-screen display controller 7A receives the character data and converts it into the digital character signal sequence.
The video signal D/A converter 7B converts the decoded digital signal sequence from the MPEG1 decoder 78 and the digital character signal sequence from the on-screen display controller 7A into the analog video signals.
The audio signal D/A converter converts the CD-DA signal sequence from the MPEG1 decoder 78 into the analog audio signals.
Next, in FIG. 11, a second example of the conventional optical disc playback apparatus is shown. An optical disc playback apparatus OPC2 of the example includes an MPEG1 decoder 88 in which the MPEG1 decoder 78 and the on-screen display controller 7A of the optical disc playback apparatus OPCL shown in FIG. 10 are integrally constructed.
Consequently, the MPEG1 decoder 88 converts the character display information and the character data from the system controller 76 into the digital character signal sequence. Further, the MPEG1 decoder 88 can output the converted digital character signal sequence together with the decoded digital signal sequence. Since the operation of the optical disc playback apparatus OPC2 for playing back the optical disc Od is basically the same as that of the optical disc playback apparatus OPC1 except for the above described operation related to the MPEG1 decoder 88, the description thereof is omitted herein.
With the conventional configurations exemplarily described in the above, however, the number of display lines of the on-screen message on a television screen is fixed to 10 whether the television image displayed thereon is in the PAL format or the NTSC format. As a result, if the on-screen display controller sets the on-screen message to be arranged evenly on the television screen in the NTSC format, the display lines of such message are upwardly shifted by approximately 20% of the screen when displayed on the television screen in the PAL format.
In FIG. 12, shown is one example of the on-screen message set for the NTSC format screen being displayed on the television screen in the PAL format. On the left half of the drawing, an on-screen message MSG is shown. Here, the on-screen message MSG is displayed on the television screen in the NTSC format with a total character display lines of 10 indicated by lines Ln 1 to Ln 10, which are evenly arranged thereon.
On the right half of the drawing, shown is a screen display MSGc, where the on-screen message MSG is displayed on the television screen in the PAL format.
The PAL format adopts 625 vertical scanning lines while the NTSC format adopts 525 vertical scanning lines. That is, the PAL format has approximately 1.2 times scanning lines when compared with the NTSC format. Therefore, assuming the space between the lines of the on-screen message is kept the same as that of the NTSC format screen, the PAL format screen has a display region of 12 lines shown as Lp 1 to Lp 12.
Accordingly, if the message MSG is displayed on the PAL format television screen without being changed in its number of character display lines, which is fixedly set to 10 for the NTSC format, a display region of approximately 2 lines remain unused. Although the example in the drawing shows the case with the bottom 2 lines of the PAL format screen (Lp 11, Lp 12) remain unused, it is needless to say that the same may be happen for the top 2 lines (Lp 1, Lp 2).
The present invention aims to solve the problem above and to provide an optical disc playback apparatus capable of properly displaying the on-screen message on a screen. When playing back a video CD, Karaoke CD, or DVD, a type of the optical disc and an image display format predetermined for data being reproduced are determined, and based on the determination, the number of character display lines of an on-screen message is set.
In more detail, an object of the present invention is to provide an optical disc playback apparatus capable of setting the number of character display lines of an on-screen message to 10 for the video in the NTSC format and to 12 for the video in the PAL format. Thus, the on-screen message is displayed on a television screen without the character display region being shifted even for the video in the PAL format. The unused portion in the bottom of the display region can be utilized to display the characters evenly on the entire screen.
A first aspect of the present invention is directed to an optical disc playback apparatus for reproducing data recorded on an optical disc and outputting an on-screen message to be displayed in a predetermined number of lines. The apparatus in accordance with the first aspect of the present invention comprises a reader for reading record data from a recording surface of the optical disc; an on-screen message generator for generating a digital character signal sequence to be displayed as the on-screen message; and an on-screen message lines controller for controlling the on-screen message generator to change a number of lines in which the on-screen message is displayed based on the record data.
As described above, in the first aspect, the number of display lines of the on-screen message can be set appropriately depending on the data recorded on the optical disc.
According to a second aspect, in the first aspect, the apparatus further comprises an optical disc determination unit for determining atype of the optical disc based on the record data, wherein the on-screen message lines controller controls the on-screen message generator to set the number of lines in which the on-screen message is displayed to 10 lines when the optical disc is determined as a music CD.
As described above, in the second aspect, the number of display lines of the on-screen message can be set appropriately depending on the type of the optical disc.
According to a third aspect, in the second aspect, the apparatus further comprises a display format determination unit for determining a display format of the data to be reproduced based on the record data wherein the on-screen message lines controller controls the on-screen message generator to set the number of lines in which the on-screen message is displayed to 10 lines when the optical disc is determined as a disc other than the music CD and when the display format of the data to be reproduced is determined as an NTSC format.
As described above, in the third aspect, the effect in the second aspect can be similarly obtained.
According to a fourth aspect, in the second aspect, the apparatus further comprises a display format determination unit for determining a display format of the data to be reproduced based on the record data, wherein the on-screen message lines controller controls the on-screen message generator to set the number of lines in which the on-screen message is displayed to 12 lines when the optical disc is determined as a disc other than the music CD and when the display format of the data to be reproduced is determined as a PAL format.
As described above, in the fourth aspect, the effect in the third aspect can be similarly obtained.
According to a fifth aspect, in the first aspect, the apparatus further comprises a display format optical determination. unit for determining a display format of the data to be reproduced based on the record data, wherein the on-screen message lines controller controls the on-screen message generator to set the number of lines in which the on-screen message is displayed to 10 lines when the display format of the datato be reproduced is determined as an NTSC format.
As described above, in the fifth aspect, in addition to the effect obtained in the first aspect, the number of display lines of the on-screen message can be set appropriately for data varying in the display format on the same optical disc.
According to a sixth aspect, in the first aspect, the apparatus further comprises a display format optical determination unit for determining a display format of the data to be reproduced based on the record data wherein the on-screen message lines controller controls the on-screen message generator to set the number of lines in which the on-screen message is displayed to 12 lines when the display format of the data to be reproduced is determined as a PAL format.
As described above, in the sixth aspect, the effect in the fifth aspect can be similarly obtained.
According to a seventh aspect, in the second aspect, the optical disc determination unit determines the type of the optical disc based on a control bit of a TOC included in the record data.
According to an eighth aspect, in the third aspect, the display format determination unit determines the display format of the data to be reproduced based on a sequence header included in the record data.
According to a ninth aspect, in the first aspect, the apparatus further comprises a signal sequence separator for separating a first music CD signal sequence and a non-music CD signal sequence which is a signal sequence other than the first music CD signal sequence; a digital signal processor for converting video signals included in the separated non-music CD signal sequence into a decoded digital signal sequence and converting audio data included in the non-musicCD signal sequence into a second music CD signal sequence; a video signal converter for converting the decoded digital signal sequence and the digital character signal sequence into analog video signals; and an audio signal converter for converting the first music CD signal sequence and the second music CD signal sequence into analog audio signals.
According to a tenth aspect, in the ninth aspect, the digital signal processor is capable of decoding an MPEG2 signal sequence.
According to an eleventh aspect, inthe ninth aspect, the digital signal processor is capable of decoding an MPEC4 signal sequence.
A twelfth aspect of the present invention is directed to an optical disc playback method for reproducing data recorded on an optical disc and outputting an on-screen message to be displayed in a predetermined number of lines. The method in accordance with the twelfth aspect of the present invention comprises reading record data from a recording surface of the optical disc; and generating a digital character signal sequence to be displayed as the on-screen message and chanying a number of lines in which the on-screen message is displayed based on the record data.
As described above, in the twelfth aspect, the number of display lines of the on-screen message can be set appropriately depending on the data recorded on the optical disc.
These and other objects, features, aspects and advantages of the present invention will become more apparent from the following detailed description of the present invention when taken in conjunction with the accompanying drawings.